Precipitation well spiral drilling machine coping with anisotropy of soil layer permeability coefficient and construction method

Abstract

The invention discloses a dewatering well spiral drilling machine coping with soil layer permeability coefficient anisotropy and a construction method, and belongs to the technical field of dewatering wells. A dewatering well spiral drilling machine coping with soil layer permeability coefficient anisotropy comprises a drill rod and a drill bit rod coaxially connected to the lower end of the drill rod, spiral blades are arranged on the drill bit rod, and the dewatering well spiral drilling machine is characterized in that the drill rod is of a hollow structure, and a mud suction hole and a sand blasting hole are formed in the side face of the lower portion of the drill rod; the mud suction hole is connected with the end, extending into the drill rod, of a mud suction pipe of the slurry discharging unit, the other end of the mud suction pipe penetrates out of the drill rod to be communicated with water pumping equipment and a slag discharging pool, the sand blasting hole is connected with the end, extending into the drill rod, of a sand blasting pipe of the grouting unit, and the other end of the sand blasting pipe penetrates out of the drill rod to be connected with a high-pressure pump. A mesh is arranged at the mud suction hole, and the aperture of the mesh is smaller than the particle size of coarse sand sprayed by the sand blasting pipe. The method can effectively cope with construction of the descending water well under the soil layer condition with anisotropic permeability coefficients.

Description

Technical Field

[0001] The present invention relates to a precipitation well spiral drilling machine for dealing with anisotropic permeability coefficient of soil layers. The present invention also relates to a method for constructing a precipitation well by using the precipitation well spiral drilling machine for dealing with anisotropy of permeability coefficient of soil layers, belonging to the technical field of precipitation wells. Background Art

[0002] The permeability coefficient is also known as the hydraulic conductivity coefficient. In isotropic media, it is defined as the unit flow rate under a unit hydraulic gradient, which indicates the difficulty of passing through the pore skeleton. Natural sedimentary soils are often composed of soil layers with different permeabilities and are macroscopically heterogeneous. When excavating foundation pits in areas rich in groundwater, the bottom plate is often below the groundwater level. It is usually necessary to conduct precipitation to lower the water level to a certain depth below the bottom plate to ensure the stability of the foundation pit and the safety of the foundation pit excavation. If precipitation is not handled properly, it may not only lead to a large amount of water accumulation in the pit, but also cause water bubbling, pipe gushing, and sudden gushing at the bottom of the pit, affecting the stability of the foundation pit. When there are interlayers or interlayers in the confined aquifer on the site, the permeability performance will have a certain anisotropy. At this time, the anisotropy of the permeability coefficient of the soil layer will cause the pumping efficiency of the precipitation well to decrease.

[0003] To solve this problem, existing technologies often use methods such as changing the depth of underground continuous walls and filter pipes inserted into the confined aquifer, optimizing the layout of precipitation wells, and changing the diameter of precipitation wells. However, the above methods are not universal and need to be redesigned according to different projects. For example, the method of optimizing the layout of precipitation wells has many process flows and high requirements on workers' construction skills. Therefore, a precipitation device that can cope with the anisotropy of soil permeability is needed. Summary of the invention

[0004] In view of the above-mentioned defects existing in the prior art, the present invention provides a spiral drilling rig for drainage wells that can cope with the anisotropic permeability coefficient of soil layers. It can cope with the construction of drainage wells under the conditions of anisotropic permeability coefficient of soil layers, and can adjust the permeability coefficient of each soil layer to improve the drainage efficiency.

[0005] The present invention is realized through the following technical scheme: a spiral drilling rig for a dewatering well for coping with anisotropic permeability coefficient of soil layers, comprising a drill rod, a drill bit rod coaxially connected to the lower end of the drill rod, and a spiral blade arranged on the drill bit rod, wherein the drill rod is characterized in that: the drill rod is a hollow structure, and a mud suction hole and a sand blasting hole are opened on the lower side of the drill rod, the mud suction hole is connected to one end of the mud suction pipe of the slurry discharge unit extending to the inside of the drill rod, and the other end of the mud suction pipe passes through the drill rod to be connected to the pumping equipment and the slag discharge pool, the sand blasting hole is connected to one end of the sand blasting pipe of the grouting unit extending to the inside of the drill rod, and the other end of the sand blasting pipe passes through the drill rod and is connected to a high-pressure pump; a mesh is arranged at the mud suction hole, and the aperture of the mesh is smaller than the particle size of the coarse sand sprayed by the sand blasting pipe.

[0006] In the present invention, the spiral drill bit formed by the drill rod and the spiral blades can rotate and penetrate into the soil layer under the vertical pressure of the drilling machine to form a borehole. The high-pressure pump can spray water and coarse sand or spray replacement soil around the borehole through the sandblasting hole of the drill rod through the sandblasting pipe, and the slurry discharge unit can suck the slurry in the borehole through the mud suction hole of the drill rod through the mud suction pipe and discharge it. The mesh provided at the mud suction hole is used to prevent the coarse sand sprayed from the sandblasting hole from being sucked into the mud suction hole.

[0007] The present invention also provides a method for constructing a precipitation well for coping with anisotropic permeability coefficient of soil layers, which is characterized by using the above-mentioned precipitation well spiral drilling machine for coping with anisotropy of permeability coefficient of soil layers to carry out construction, comprising the following steps:

[0008] (1) Construction preparation: determine the location of the dewatering well and prepare construction materials, slag discharge pool, high-pressure pump, and pumping equipment to ensure that the construction site is clean and safe;

[0009] (2) Surveying and setting out: Before construction, set out the benchmark points, control axis lines, and well locations according to the drawings, use a level to measure the ground elevation of the well location, and make well location marks;

[0010] (3) Drilling rig in place: transport the drilling rig to the location of the dewatering well, and install and debug it to ensure that the drilling rig is level and stable, and the well position is accurate and the deviation does not exceed the specified requirements;

[0011] (4) Drill bit centering and straightening: Slowly lower the drill bit to 20-30 cm above the ground, and then fine-tune the drill rig so that the center axis of the drill bit is aligned with the guide hole position;

[0012] (5) Drilling construction: During the drilling process, the spiral blades are used to rotate and cut the soil. During the drilling process, the drilling speed is adjusted at any time according to the geological data of different soil layers.

[0013] (6) Generating a horizontal drainage body: When the drill enters a soil layer with a low vertical permeability coefficient, start the high-pressure pump to spray water and coarse sand through a sandblasting tube to form a coarse sand horizontal drainage body inside the soil layer or replace the soil layer by spraying replacement soil through a sandblasting tube. At the same time, the soil cut by the spiral blade is mixed with water to form mud, and the mud is extracted through a mud suction pipe to form a hole;

[0014] (7) Retract the auger drilling equipment: stop the construction equipment and vertically lift out the auger drilling equipment.

[0015] In the present invention, water and coarse sand are sprayed into the soil layer with a small vertical permeability coefficient by using a grouting unit to form a coarse sand horizontal drainage body inside the soil layer or directly replace the soil layer, thereby combining the coarse sand cushion layer or replacement soil layer as a horizontal drainage body with the precipitation well as a vertical drainage body. The formed coarse sand horizontal drainage body or replacement soil layer is used to adjust the permeability of the soil layer around the precipitation well, which can effectively improve the drainage effect of the precipitation well.

[0016] Furthermore, in step (6), after the high-pressure pump is started, high-pressure water is firstly sprayed through the sandblasting tube to cut the soil, and then water and coarse sand are sprayed to form a coarse sand horizontal drainage body or replacement soil is sprayed to replace the soil layer.

[0017] Furthermore, the coarse sand horizontal drainage bodies or replacement soil layers formed have multiple axially arranged in the soil layer space centered on the drainage well. The number, vertical position, etc. of the coarse sand horizontal drainage bodies or replacement soil layers can be set according to the designed drainage effect.

[0018] Furthermore, in step (6), the power of the high-pressure pump is adjusted according to the permeability coefficient to form coarse sand horizontal drainage bodies or replacement soil layers of different diameters around the borehole, thereby adapting to the anisotropy of the permeability coefficient of the soil layer.

[0019] The beneficial effects of the present invention are as follows: the present invention can cope with the construction of a drainage well under the condition of anisotropic permeability coefficient soil layer, the position and range of the coarse sand horizontal drainage body formed can be adjusted, and the problem of reduced drainage efficiency caused by the anisotropy of the lateral and vertical permeability coefficients of the layered soil can be solved. The coarse sand horizontal drainage body can be formed inside the soil layer with a very small vertical permeability coefficient or the soil layer can be directly replaced through the grouting and slurry discharge unit, thereby combining the coarse sand cushion layer or replacement soil layer as the horizontal drainage body with the drainage well as the vertical drainage body, adjusting the permeability coefficient of each soil layer, and effectively improving the drainage efficiency of the drainage well, ensuring the drainage effect of the foundation pit, and ensuring the stability of the foundation pit and the safety of the foundation pit excavation. The construction method of the present invention is simple, has strong adaptability, and has a fast construction speed, which can effectively ensure the construction period and reduce the project cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a structural schematic diagram of the drilling part of the spiral drilling machine for a precipitation well that can cope with the anisotropy of the permeability coefficient of the soil layer in the present invention;

[0021] Figure 2 yes Figure 1 A schematic cross-sectional view of the middle drill pipe portion;

[0022] Figure 3 It is a process flow diagram of a construction method of a precipitation well for dealing with anisotropy of soil permeability coefficient in the present invention;

[0023] Figure 4It is a cross-sectional view of the combination of the horizontal and vertical drainage bodies after construction in the present invention;

[0024] In the figure, 1. slag discharge pool, 2. high-pressure pump, 3. sandblasting pipe, 4. mud suction pipe, 5. mud suction hole, 6. sandblasting hole, 7. drill rod, 8. drill bit rod, 9. spiral blade. DETAILED DESCRIPTION

[0025] The present invention will be further described below by way of non-limiting embodiments and in conjunction with the accompanying drawings:

[0026] As attached Figure 1 and Figure 2 As shown, a spiral drilling machine for a dewatering well for dealing with anisotropic permeability coefficient of soil layers comprises a drill rod 7, a drill rod 8 coaxially connected to the lower end of the drill rod 7, and a spiral blade 9 is arranged on the drill rod 8. The two constitute a spiral drill bit, which can rotate and drill into most soil layers including hard rock, and the drilling is stronger than that of an ordinary non-spiral drill bit. The drill rod 7 is a hollow structure, and a mud suction hole 5 and a sand blasting hole 6 are opened on the lower side of the drill rod 7. The mud suction hole 5 is connected to one end of the mud suction pipe 4 of the slurry discharge unit extending to the inside of the drill rod 7, and the other end of the mud suction pipe 4 passes through the drill rod 7 to connect with the pumping equipment and the slag discharge pool 1, and the sand blasting hole 6 is connected to one end of the sand blasting pipe 3 of the grouting unit extending to the inside of the drill rod 7, and the other end of the sand blasting pipe 3 passes through the drill rod 7 and is connected to the high-pressure pump 2. The slurry discharge unit is used to discharge the mud in the borehole through the pumping equipment, and the grouting unit is used to inject water and coarse sand into the borehole through the high-pressure pump. A mesh is provided at the mud suction hole 5 , and the aperture of the mesh is smaller than the particle size of the coarse sand sprayed by the sandblasting tube 3 .

[0027] As attached Figure 1-Figure 4 As shown, this embodiment also discloses a method for constructing a precipitation well for coping with anisotropic permeability coefficient of soil layers, which is constructed by using the above-mentioned precipitation well spiral drilling machine for coping with anisotropy of permeability coefficient of soil layers, and includes the following steps:

[0028] (1) Construction preparation: determine the location of the dewatering well and prepare construction materials, slag discharge pool, high-pressure pump, and pumping equipment to ensure that the construction site is clean and safe;

[0029] (2) Surveying and setting out: Before construction, benchmark points, control axes, and well locations are set according to the design and construction plan of the dewatering project. The ground elevation of the well location is measured with a level and the well location is marked;

[0030] (3) Drilling rig in place: transport the drilling rig to the location of the dewatering well, and install and debug it to ensure that the drilling rig is level and stable, and the well position is accurate and the deviation does not exceed the specified requirements;

[0031] (4) Drill bit centering and straightening: The commander instructs the driver to slowly lower the drill bit to 20-30 cm from the ground, and then fine-tune the drill rig so that the center axis of the drill bit is aligned with the pilot hole position;

[0032] (5) Drilling construction: During the drilling process, the spiral blades of the drilling rig rotate and cut the soil. During the drilling process, the geological data are compared according to the conditions of different soil layers, and the drilling speed is adjusted at any time. During the drilling process, the drill rod should not be reversed or lifted. During the drilling process, if the drill is stuck, the drill rig shakes, deflects, or an abnormal sound occurs, the drilling should be stopped immediately, the cause should be found out, and the operation can be continued only after taking appropriate measures;

[0033] (6) Generating a horizontal drainage body: When the drill enters a soil layer with a small vertical permeability coefficient, the high-pressure pump is started to spray water and coarse sand through the sandblasting tube introduced by the drill pipe to form a coarse sand horizontal drainage body inside the soil layer or to directly replace the soil layer by spraying replacement soil through the sandblasting tube. The power of the high-pressure pump can be adjusted according to the permeability coefficient to adapt to the anisotropy of the permeability coefficient of the soil layer and achieve the expected precipitation effect; at the same time, the soil cut by the spiral blade is mixed with water to form mud, and the mud is extracted through the mud suction pipe to form a hole;

[0034] (7) Retract the auger drilling equipment: stop the construction equipment and vertically lift out the auger drilling equipment.

[0035] The drilling rig used in this embodiment has the same structure as the existing drilling rig except for the drill rod and the spiral drill bit.

[0036] In the present invention, when generating a horizontal drainage body, after starting the high-pressure pump, high-pressure water can be sprayed through the sandblasting tube to cut the soil body, and then water and coarse sand can be sprayed to form a coarse sand horizontal drainage body or replacement soil can be sprayed to replace the soil layer.

[0037] In the present invention, the number, vertical position, range, etc. of the coarse sand horizontal drainage body or the replacement soil layer can be set according to the designed drainage effect. The coarse sand horizontal drainage body or the replacement soil layer formed can have multiple axial directions in the soil layer space centered on the precipitation well. By adjusting the power of the high-pressure pump, the radial injection distance can be adjusted, and cylindrical horizontal drainage bodies of different diameters can be formed to adapt to the anisotropy of the permeability coefficient of the soil layer and achieve the expected precipitation effect. The method of directly replacing the soil layer is mainly used in the case where the soil layer that needs to adjust the permeability coefficient is thin or is only a soil layer sandwich.

[0038] The invention has a simple process and a fast construction speed. By adjusting the permeability coefficient of each soil layer, the drainage efficiency of the precipitation well can be effectively improved, and the foundation pit precipitation efficiency can be effectively improved, thereby reducing the project cost and having a high economic value.

[0039] The other parts of this embodiment are all prior art and will not be described in detail here.

Claims

1. A spiral drilling machine for a drainage well for coping with anisotropic permeability coefficient of soil layers, comprising a drill rod (7), a drill bit rod (8) coaxially connected to the lower end of the drill rod (7), and a spiral blade (9) provided on the drill bit rod (8), wherein: The drill rod (7) is a hollow structure. A mud suction hole (5) and a sand blasting hole (6) are provided on the lower side of the drill rod (7). The mud suction hole (5) is connected to one end of the mud suction pipe (4) of the slurry discharge unit extending into the drill rod (7). The other end of the mud suction pipe (4) passes through the drill rod (7) to connect with the pumping equipment and the slag discharge pool (1). The sand blasting hole (6) is connected to one end of the sand blasting pipe (3) of the grouting unit extending into the drill rod (7). The other end of the sand blasting pipe (3) passes through the drill rod (7) to connect with the high-pressure pump (2). A mesh is provided at the mud suction hole (5). The mesh has a hole diameter smaller than the particle diameter of the coarse sand sprayed by the sand blasting pipe (3).

2. A construction method for a precipitation well to cope with anisotropy of soil permeability, characterized by: The construction of a dewatering well spiral drilling machine for dealing with anisotropic soil permeability coefficient according to claim 1 comprises the following steps: (1) Construction preparation: determine the location of the dewatering well and prepare construction materials, slag discharge pool, high-pressure pump, and pumping equipment to ensure that the construction site is clean and safe; (2) Surveying and setting out: Before construction, set out the benchmark points, control axis lines, and well locations according to the drawings, use a level to measure the ground elevation of the well location, and make well location marks; (3) Drilling rig in place: transport the drilling rig to the location of the dewatering well, and install and debug it to ensure that the drilling rig is level and stable, and the well position is accurate and the deviation does not exceed the specified requirements; (4) Drill bit centering and straightening: Slowly lower the drill bit to 20-30 cm above the ground, and then fine-tune the drill rig so that the center axis of the drill bit is aligned with the guide hole position; (5) Drilling construction: During the drilling process, the spiral blades are used to rotate and cut the soil. During the drilling process, the drilling speed is adjusted at any time according to the geological data of different soil layers. (6) Generating a horizontal drainage body: When the drill enters a soil layer with a low vertical permeability coefficient, start the high-pressure pump to spray water and coarse sand through a sandblasting tube to form a coarse sand horizontal drainage body inside the soil layer or replace the soil layer by spraying replacement soil through a sandblasting tube. At the same time, the soil cut by the spiral blade is mixed with water to form mud, and the mud is extracted through a mud suction pipe to form a hole; (7) Retract the auger drilling equipment: stop the construction equipment and vertically lift out the auger drilling equipment.

3. The construction method of a precipitation well according to claim 2, characterized in that: In step (6), after starting the high-pressure pump, high-pressure water is firstly sprayed through the sandblasting tube to cut the soil, and then water and coarse sand are sprayed to form a coarse sand horizontal drainage body or replacement soil is sprayed to replace the soil layer.

4. The construction method of a precipitation well according to claim 2, characterized in that: The coarse sand horizontal drainage bodies or replacement soil layers formed have multiple axial directions in the soil layer space centered on the precipitation well.

5. The construction method of the precipitation well according to claim 2, 3 or 4, characterized in that: In step (6), the power of the high-pressure pump is adjusted according to the permeability coefficient to form a coarse sand horizontal drainage body or replacement soil layer of different diameters around the borehole, thereby adapting to the anisotropy of the permeability coefficient of the soil layer.

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